1. Field of the Invention
The present invention relates to a filter element to be incorporated into an air cleaner which filtrates or purifies air to be sucked into an internal combustion engine, and also relates to a method of manufacturing such a filter element.
2. Description of the Prior Art
A conventional air cleaner is found in, for example, Japanese Utility Model Publication No. 63-18423. As shown in FIG. 13, the prior art air cleaner 136 is mainly constituted of a lower case 131, an upper case 133, and a filter element 132 arranged between the cases 131 and 133. The lower case 131 and the upper case 133 are provided with an air intake pipe 130 and an air outlet pipe 134 extending therefrom, respectively. The air outlet pipe 134 is connected to an engine (not shown). Air sucked through the intake pipe 130 passes through the filter element 132 and enters the engine through the air outlet pipe 134 when the engine is in an operative condition. As will be appreciated, the air is purified as it passes through the filter element 132. Further, the upper case 133 is detachably combined with the lower case 131 by clamps 135 to facilitate disassembly of the air cleaner 136 so as to replace the filter element 132 with a new one.
A conventional filter element is found in, for example, Japanese Laid-Open Utility Model Publication No. 1-101615. As shown in FIG. 11, the prior art filter element 110 includes a filter medium 111, a rectangular frame member 112 and a cushioning member 113 made of a synthetic elastomeric resin. The filter medium 111 is made of a sheet-like material which is folded in a sawtooth-shaped pattern to maximize the total surface area thereof. The filter medium 111 extends along a plane S and has a substantially rectangular base contour 111a which is contained in the plane S. As will be appreciated, the filter medium 111 has opposed sawtooth-shaped edge sections extending along opposed base contour sections 111b of the base contour 111a. Air is filtrated or purified when the air is transferred from one side of the plane S (the upper side in the drawing) to the other side of the plane S (the lower side in the drawing).
The filter medium 111 is incorporated into the frame member 112. The frame member 112 includes a flange 112a outwardly integrally projecting therefrom and two pairs of opposed vertical walls 112b and 112c integrally formed on the flange 112a. The flange 112a confines the base contour 111a of the filter medium 111. The walls 112b extends along the base contour sections 111b of the base contour 111a and is airtightly bonded to the sawtooth-shaped peripheral edge sections of the filter medium 111. Further, the walls 112b have sawtooth-shaped configuration so as to conform to the sawtooth-shaped peripheral edge sections of the filter medium 111. As best shown in FIG. 12, the cushioning member 113 is circumferentially provided on the peripheral edge of the flange 112a so as to cover the upper surface, the end edge and the lower surface of the flange 112a.
When the filter element 110 thus constructed is applied to the air cleaner 136 shown in FIG. 13, the cushioning member 113 may act as a gasket to provide excellent airtight seals between the filter element 110 and the upper case 133 and between the filter element 110 and the lower case 131 for effectively preventing entrance of the nonpurified air into the upper case 133 through the spaces between the upper case 133 and the lower case 131 since the cushioning member 113 is made of the synthetic elastomeric resin which exhibits resistivity to air transmission and good deformability. As will be easily understood, if the filter element 110 does not have the cushioning member 113 provided on the flange 112a, the air introduced into the engine may contain nonpurified air which is sucked through spaces between the upper case 133 and the lower case 131.
A described above, the filter element 110 shown in FIGS. 11 and 12 uses the cushioning member 113 made of the synthetic elastomeric resin. The cushioning member 113 has to exhibit suitable elasticity for a long time in an engine room of which the temperature environment is vigorously changed. Thus, the cushioning member 113 has to be made of a high quality synthetic elastomeric resin. This may lead to increased cost of the filter element 110. Additionally, the filter element 110 is not suitable for reuse since the cushioning member 113 is made of the synthetic elastomeric resin different from a material for the frame member 112.
It is an object of the invention to provide a filter element which can be manufactured at relatively low cost.
It is another object of the invention to provide a filter element which is suitable for reuse.